Heat the oven to 180°C/350°F/Gas Mark 4. To make the sponge, put the butter into a large mixing bowl, or the bowl of a free-standing electric mixer fitted with the whisk attachment, and beat until creamy with a hand-held electric whisk, or the whisk attachment. Add the sugar and zest and beat in thoroughly, scraping down the sides of the bowl from time to time, until the mixture is light and fluffy.

Gradually add the eggs, beating well after each addition, and scraping down the sides as before – it’s a good idea to add a tablespoon of the weighed flour with each of the last three additions of egg. Sift the rest of the flour into the bowl and gently fold in using a spatula.

Transfer the mixture to the prepared tins, dividing it equally, and spread evenly. Bake in the heated oven for about 35 minutes until well risen, golden brown and springy when gently pressed in the centre; a skewer inserted into the centre should come out clean.

While the cakes are baking, make the candied peel and the drizzle. For the candied peel, carefully remove strips of peel from the lemon and orange using a vegetable peeler – leave as much white pith behind on the fruit as possible (squeeze the juice from the fruit to use in the curd).

Trim the peel to neaten the edges, then put it into a medium pan of cold water. Bring to the boil and simmer for about 10 minutes until tender. Drain. Put the measured water and sugar into the empty pan and stir over low heat until the sugar has dissolved. Bring to the boil, then add the drained peel. Simmer for 20-30 minutes until the peel looks translucent. Drain the peel thoroughly, then spread out on a sheet of baking paper and dust with caster sugar. Leave until cold.

To make the drizzle, stir the sugar with the lemon juice in a bowl until dissolved. Set aside.

When the cakes are baked, run a round-bladed knife around the inside of each tin, unclip the side and turn out the sponge on to a wire rack. Place a plate underneath the rack to catch drips. Prick the sponges well with a cocktail stick, then spoon over the drizzle syrup. Leave to cool.

Meanwhile, make the orange curd. Put the egg yolks, sugar, orange zest and juice, and lemon juice into a medium-sized heavy-based pan and whisk with a hand wire whisk until thoroughly combined. Set over low heat and stir constantly with a wooden spoon until the sugar has completely dissolved, then turn up the heat to medium and continue stirring as the mixture comes to a simmer.

Keep stirring as the mixture simmers and thickens to a consistency that will coat the back of the spoon – this will take 8-10 minutes. If necessary, move the pan on and off the heat so the mixture keeps to a gentle simmer. Remove the pan from the heat and gradually stir in the butter. Transfer to a heatproof bowl, press a sheet of clingfilm on the surface (to prevent a skin from forming) and leave to cool, then chill until firm enough to spread easily.

To make the icing, sift the icing sugar into a mixing bowl and gradually stir in enough lemon juice to make a smooth, thick but flowing icing. Keep covered until needed.

To assemble the cake, set one sponge, crust-side down, on a plate or board. Spread the orange curd over the surface, then set the other sponge on top, crust-side up. Spoon the icing over the top and allow it to flow gently to the edge and just over it. Add the candied peel decoration. Leave to firm up before serving.